Thread-cutting device for sewing-machines.



PATENTED AUG. 27,1907. R.L.LYONS. THREAD CUTTING DEVICE FOR SEWING MACHINES.

APPLICATION FILED PEB- B. 1904.

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PATENTED AUG. 27, 1907. R. L. LYONS.

THREAD CUTTING DEVIGE'POR SEWING MACHINES.

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. R.L.LYONS'. THREAD GUTTINGDEVIGE FOR SEWING MACHINES.

APPLICATION FILED FEB. 8. 1904.

PATENTED AUG. 27, 19Q7 Jaw W mm [wax/27 "RM if ms mmnls psrsns co., wxsnmarou, n. a.

UNITED STATES PATENT OFFICE.

THREAD-CUTTING DEVICE FOR SEWING-MACHINES.

Specification of Letters Patent.

Patented Augn 27, 1907.

Application filed February 8, 1904- Serial No. 192,581-

To all whom it may concern:

Be it known that 1, ROBERT L. LYONS, of Waltham, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Thread-Cutting Devices for Sewing-Machines; and I hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings,-forming part of this speciby the movement of apparatus set in motion by the operator after the completion of the sewing.

Another object of the invention is to cut the threads without interfering with the passage of the needle.

Other objects will appear from the following description.

The invention consists in such novel features of construction and combination of parts as shall hereinafter be more fully described and pointed out in the claims.

Figure 1, represents an end elevation of parts of a sew ing machine illustrating this invention. Fig. 2, represents a plan view, partly in section, showing the position of the parts during the sewing operation, or immediately thereafter. Fig. 3, represents a similar view illustrating the limit of movement of the parts to effect the cutting of the threads. Fig. 4, represents a vertical section on line 44, Fig. 2, showing theposition of the threads at the completion of the sewing. Fig. 5, represents an end elevation of parts of a sewing machine to which this improvement is applied, the presser foot and the lever for raising the same also being shown.

Similar numbers of reference designate corresponding parts throughout.

The present thread cutting devices are preferably intended to operate before the take up for the needle thread has completed its upward movement and during the first part of a downward movement of the needle, the machine being adjusted, in the well known manner, to stop at this point in order that sufiicient room may be had below the point of the needle, asshown in Fig. l, for the readjustment of heavy work. In stopping at this point in the operation, the last loop of the needle thread is not drawn tightly into the work and a depending loop, of greater or less length, is left below the work, this loop being cut away, as also the shuttle thread by the thread cutting devices.

As shown in the drawings, in its preferred form, 10 represents the usual bed plate of any well known two thread sewing machine having the head 11, in which is movably mounted, and driven in any manner, the nee dle bar 12 carrying the needle 13; as also the usual presser foot lifter rod 14 adapted to be elevated by the depression of the usual lifter lever 15 pivotally mounted in the head 11 in the usual manner and connected by means of the rod 16 with anysuitabletreadle, or other manually operated device under the control of the operator.

The bed plate 10 has the usual throat plate 17 having the needle hole, or passage, 18, and to the upper surface of the bed plate 10, at the rear portion thereof, are secured the strips 19 and 2,0.

On the strip 19 is pivotally mounted the cam plate 21 having the cam shoulder 22 and the upwardly extending member 23 having the inclined edge 24; while on the rod 16 is adjustably mounted the clamp 25 having the finger 2 6 which works against the inclined edge 24 of the member 23 when the rod 16 is drawn downward, as in the operation of elevating the presser, to cause the swinging of the cam plate 21.

Pivotally mounted on the strip 20 is the cutter carrying arm 27 having the extension 28, against the edge of which the cam shoulder 22 works, and furnished with the member 29 carrying the cutter plate 30 of thin material and having the opening 31, the edge 32 of which is sharpened to form acutting device; the arm 27 being connected by the retracting spring 33 with the fixed pin 34, said spring exerting a retracting strain on said arm.

As has been stated above, the machine is adjusted in the ordinary manner, to stop before the take up for the needle thread completes its upward movement, therefore a loop of such thread depends from the work as shown at A in Fig. 4, while the shuttle thread B in such figure, extends to the shuttle mechanism. When, new, the rod 16 is drawn downward to effect the lifting of the button clamp, or other presser, connected with the lifter bar 14, the finger 26 carried by the rod 16 works against the inclined edge 24 of the plate 23 and causes the swinging of the cam plate 2] thus causing the cam shoulder 22 to bear against the member 28 of the cutter carrying arm 27 and effecting the positive actuation of said arm 27 against the retractive strain of the spring 33 and moving the edge 32 of the cutter plate 30 across the path of the needle and cutting away the loop A, of the needle thread, and the shuttle thread B close to the under surface of the work 0 as the cutter works over the edge of the needle hole.

It is of course obvious that the edge of the needle hole may represent the cutting element and the plate 30 may represent the moving element which carries the threads, both upper and lower, against the fixed cutting element thus represented by the edge of the needle hole.

When the rod 16 is released, to permit the depression of the presser, the arm 27 is retracted by the spring thread below the work at a single operation and this without the use of delicate mechanism for engaging and holding either of said threads at or before the cutting of the same. I therefore do not limit myself to the particular construction herein shown and described. Nor do I desire to limit myself entirely to the use of the present cutter for cutting both threads simultaneously as it may become desirable in some cases to draw the needle thread upward out of the path of the cutter.

Having thus described my invention, I claim as new and desire to secure by Letters Patent.

1. In a sewing machine, the combination with an arm.

pivotally mounted above the throat plate and carrying a thread cutter, of the presser foot, the presser foot elevating mechanism the treadle rod for actuating the presser foot elevating mechanism, a cam pivotally mounted to work against the first mentioned arm, and means carried by the treadle rod for causing the swinging of said cam for the purpose described.

2. In a sewing machine, the combination with the bed plate, the throat plate having a needle hole, and an arm pivotally mounted on the bed plate and having a cutting edge, adapted to work across the needle hole, and a laterall-y extending member, of a cam member pivotally mounted on said bed plate and working against said member and having a vertical member furnished with an inclined edge, the treadle connection to the presser foot lifter, such lifter, and means on said connection adapted to work against the inclined edge ofrthe canrmember to effect the swinging of the cam as and for the purpose described.

3. In a sewing machine, the combination with the treadle connection for effecting the lifting of the presser foot,-and a member extending from said connection, of a cam plate pivotally mounted and having an upwardly extending inclined member against which the member on the treadle connection is designed to work at times to cause the swinging of the cam plate, a cutter arm pivotally mounted and having a member against which said caln plate is designed to work to cause the swinging of the cutter arm, and a spring designed to etfect the retraction of the cutter arm, as and for the purpose described.

In testimony whereof I afiix my signature in presence of two witnesses.

ROBERT L. LYONS.

Witnesses:

II. .T. MILLER, S. GOOSTRAY. 

